Recently, a plurality of semiconductor devices are fabricated, being separated from each other by a scribe line region, on a wafer.
In fabrication, a field oxide layer is formed on a p-silicon substrate whereby a plurality of device regions and a scribe line region are formed on the substrate. Then, a photoresist layer is formed on the scribe line region entirely, and an n-impurity layer is formed on the substrate by an ion implantation using the photoresist layer as a mask. After that, the photoresist layer is removed, and a p-impurity layer is formed on the p-silicon substrate. Next, an interconnection line is formed on a periphery portion of the scribe line region entirely, whereby the interconnection line is connected through the p-impurity layer to the substrate.
According to the conventional method for fabricating semiconductor devices, however, there is a disadvantage in that electric charge which is generated by ion implantation is accumulated in the device regions, because the scribe line region is covered with the photoresist layer when ion implantation is carried out to form the n-impurity layer on the substrate. Therefore, the electric charge can not be transferred through a surface of the substrate due to low surface conduction by the encircling photoresist layers, whereby electrostatic discharge occurs in the device regions. As a result, semiconductor devices to be fabricated on the wafer may be broken by the electrostatic discharge.